I have a Canon S3IS digital camera which can take movies. The movies show
an .AVI extension and (I think) use an MJPEG codec. After transferring the
movie files to my (Vista) hard drive, their behavior is erratic:

- The movie files *will not* play in Windows Media Player. The WMP error
message is: "Windows Media Player encountered a problem while playing the
file". Clicking on Web Help reveals: "You've encountered error message
C00D11B1 while using Windows Media Player."

- The movie files *will not* play in Windows Media Center; WMC says "Cannot
Play Video - Windows Media Center cannot open the file".

- If I import the files into Windows Movie Maker, WMM appears to play them,
but the preview screen is black.

- GSpot reports that the file is a Motion JPEG, and that "Codec(s) are
Installed".

- The movie files *will* play using Canon's ZoomBrowser EX program (came
with the camera).

Related Info:

- Both WMP & WMC play my .wmv files just fine. I also have one .avi file
from a different source which plays fine.
- The file extension on the AVI files that will not play is .AVI
(capitalized); the file extension on the avi file that will play is .avi
(lower case) -- probably does not matter?

Will appreciate clues on where to look to solve the issue. Thanks.